docs: def node_val_set(self, graph, node, key, branch, turn, tick, value):
          """Set a key-value pair on a node at a specific branch and revision"""
          if (branch, turn, tick) in self._btts:
              raise TimeError
          self._btts.add((branch, turn, tick))
          graph, node, key, value = map(self.pack, (graph, node, key, value))
          self._nodevals2set.append((graph, node, key, branch, turn, tick, value))